I think it would be extremely useful if users (or admins at least) could backup the files that they upload to the documents tab. This could be accomplished possibly thru a zip file.

There are several reasons for this. First and most important, is for data portability. Vendor lockin is one of the worst parts of proprietary software. Though this wouldnt make the data portable, it would at least allow for dl-ing of the files.

Such an option would give users piece of mind when they upload their files to Redmine(and I would think lower the barrier to more users joining such sites). I would even venture to hypothesize that the increase in users would outweigh anyone who took their data and left.

How this would actually work might be difficult. The increase in bandwidth loads would have to be considered if people are downloading alot. Could be fixed by limiting it to admins and only a certain number of times per week.

Either way, I know such a feature is hugely important to myself and would probably sell alot of people on using the site as the risk would be much less of ending up with another site that contains a bunch of their files.